The present invention relates to a rechargeable battery pack for a mobile terminal of a wireless telecommunication system, a mobile terminal for a wireless telecommunication system and a method for providing accurate real time information in a mobile terminal for a wireless telecommunication system.
Usual mobile terminals of wireless telecommunication systems, as e. g. the GSM system, comprise real time means generating and providing real time information for the mobile terminal. Such a real time means e. g. comprises a quartz device operating in the kHz frequency range and represents a cheap and little energy-consuming possibility of generating real time information for use in the mobile terminal. Such a mobile terminal further comprises a rechargeable battery pack which can be connected and deconnected from the mobile terminal so that, when a first rechargeable battery pack is empty, a user can replace this first rechargeable battery pack with a second rechargeable battery pack being fully charged. The first rechargeable battery pack can then be recharged while the mobile terminal is operated with the second rechargeable battery pack. In this way, a mobile terminal can be continuously used. On the other hand, in case that a rechargeable battery pack connected to a mobile terminal is empty, it has to be ensured that the real time means in the mobile terminal continues to operate. Therefore, a back-up battery is provided for the real time means of the mobile terminal in order to keep the real time information. In this way, real time information is provided in the mobile terminal even after a power fail or after a battery pack has been removed or changed.
In the prior art, different types of rechargeable battery packs are known. U.S. Pat. No. 5,248,929 proposes a battery monitoring system for a mobile terminal which provides the user with a real time display of the amount of time remaining for the use of the mobile terminal on the basis of the stored energy in the battery pack. EP 0 673 103 A1 discloses a rechargeable battery pack with an identification circuit providing the unique identification information for the battery pack and a real time clock. The battery pack can be instantly identified on the basis of the unique identification information for purposes of controlling the recharging of the battery in a respective charging apparatus. The real time clock included in the battery pack provides real time information for the mobile terminal. The mobile terminal is not provided with a real time clock means but receives the real time information from a connected battery pack.
The object of the present invention is to provide a rechargeable battery pack for a mobile terminal of a wireless telecommunication system, a mobile terminal for a wireless telecommunication system and a method for providing accurate real time information in a mobile terminal for a wireless telecommunication system, in which accurate real time information is provided in a simple, cheap and effective way.
This object is achieved by a rechargeable battery pack for a mobile terminal of a wireless telecommunication system according to claim 1, comprising one or more battery cells, time reference means for generating relative time reference information, identification means for providing unique identification information allocated to the battery pack and interface means for transmitting said unique identification information and said relative time reference information to a connected mobile terminal for updating real time information in the mobile terminal on the basis of said unique identification information.
The above object is further achieved by a mobile terminal for a wireless telecommunication system according to claim 4, comprising interface means for receiving unique identification information from a rechargeable battery pack connected to the mobile terminal, real time means for generating real time information for the mobile terminal, and control means for determining on the basis of received unique identification information if a connected battery pack has been connected before and updating said real time information on the basis of accurate time information depending on said determination result.
The above object is further achieved by a method for providing accurate real time information in a mobile terminal for a wireless telecommunication system, comprising the steps of generating real time information in the mobile terminal, receiving unique identification information from a rechargeable battery pack connected to the mobile terminal, determining on the basis of received unique identification information if a connected battery pack has been connected before, and updating the real time information on the basis of accurate time information depending on the determination result in order to obtain accurate real time information.
The present invention provides a simple, effective and cheap possibility of providing accurate real time information in a mobile terminal of a wireless telecommunication system. Particularly, the real time means in the mobile terminal according to the present invention can be implemented as a cheap and very simple real time means for generating real time information in the mobile terminal, as e. g. a software algorithm or the like. Further, no back-up means has to be provided for the real time means of the mobile terminal according to the present invention, since the real time information generated by the real time means is regularly updated when a rechargeable battery pack is connected to the mobile terminal. Therefore, there is no need in the mobile terminal according to the present invention to maintain the operation of the real time means when the battery pack is removed or changed, since every time when a charged battery pack is connected to the mobile terminal, the real time information of the real time means of the whole terminal is updated on the basis of accurate time information.
Therefore, the rechargeable battery pack and the mobile terminal according to the present invention can be produced at low cost. Further, no recycling problems of a back-up battery provided in the mobile terminal arise.
Advantageously, the rechargeable battery pack according to the present invention comprises a back-up means for backing up the time reference means when the battery pack is empty or discharged. In this case, some energy might remain in the one or more battery cells of the battery pack to provide the back-up function for the time reference means. The remaining energy, however, might not be sufficient anymore to operate the mobile terminal. In this way, the back-up function is transferred from the mobile terminal as known in the prior art to the rechargeable battery pack according to the present invention so that an extended back-up time compared to the back-up time of a normal back-up means provided in a mobile terminal as known from the prior art can be provided. For example, real time clock circuitry implemented in a complex chipset operates normally between 2.7V and 3.3V and uses 5 to 15 uA (e.g. 0.3 um process), due to other requirements of the chip-set (e.g. speed integration of different memory types, . . . ). The capacity of a standard back-up battery is in the range of 2 mAh to 4 mAh. In addition, a charging circuitry is required which needs an additional 50-100 uA quiescent current.
On the other hand an optimised simple real time clock circuitry can operate between 1V to 5V and uses normally less than 1 uA. Due to the superior voltage condition it can be operated directly from the battery pack and does not require a charging circuitry. Furthermore, a battery pack when discharged so that the phone itself is not operational any more has normally a remaining capacity above 10 mAh.
This gives an increase of the back-up time of a factor of 120 to 2500.
The above values are examples of the today""s technology. Specific values can vary dependent on the process.
If necessary, however, the mobile terminal can comprise a back-up battery connected to the real time means. The back-up battery is charged by the battery pack of the mobile terminal during operation and enables the real time means to output real time information even when the battery pack is disconnected from the mobile terminal or empty.
Advantageously, the time reference means of the rechargeable battery pack of the present invention comprises a frequency base providing a frequency signal and a counter means for converting said frequency signal into counts representing the relative time reference information.
A major advantage of the relative time reference is, that battery packs can be swaped between different users/different mobile terminals. Both users can modify the time setting without influencing the other user""s setting, since the counts in the battery pack are not modified, only the information stored in the mobile telephone.
Thereby, the frequency base may provide a very precise high frequency signal, e. g. in the MHz frequency range, so that a very accurate real time information can be obtained in a connected mobile terminal. On the other hand, the frequency base can e. g. comprise a normal quartz device providing a low frequency signal in the kHz frequency range so that a more cost-effective solution can be achieved.
As stated above, the mobile terminal according to the present invention comprises control means for determining on the basis of received unique identification information if a connected battery pack, as e. g. a battery pack according to the present invention as described above, has been connected before and for updating said real time information generated from the real time means of the mobile terminal on the basis of accurate time information depending on the determination result. Advantageously, the control means thereby updates the real time information on the basis of accurate time information input via an input means in case that a connected battery pack has never been connected before and stores said accurate time information, a relative time information received from the connected battery pack and corresponding to the time point of said accurate time information and said unique identification information in a memory means. Thus, in case that a connected battery pack is connected for the first time with the mobile terminal, which is determined on the basis of the unique identification information, the control means requests the input of an accurate time information from a user. Upon the input of said accurate time information, the control means reads the relative time reference information from the connected battery pack at the timepoint of the accurate time information and then stores the accurate time information, the relative time reference information and the unique identification information linked together in said memory means.
In this case, the control means advantageously, upon determining that a connected battery pack has been connected before, updates the real time information provided in the mobile terminal on the basis of an actual relative time reference information received from the connected battery pack as well as accurate time information and relative reference time information stored together with the unique identification information of the connected battery pack in the memory means. Thus, when a connected battery pack is connected once again with the mobile terminal which is detected by the control means by comparing the unique identification information received from the connected battery pack with the information stored in the memory means, the control means reads the accurate time information and relative reference time information stored together with the unique identification information from the memory means so that the real time information from the real time means can be updated and accurate real time information is provided in the mobile terminal.
Advantageously, the memory means of the mobile terminal is a non-volatile memory so that information stored in the memory means is maintained even when the battery pack is exchanged or empty. Further advantageously, the memory means of the mobile terminal stores accurate time information, relative time reference information corresponding to the accurate time information and unique identification information for a predetermined number of different battery packs, whereby for each battery pack the connecting timepoint is additionally stored to enable an overwriting in case that the memory means is full. The connecting timepoint is a timepoint at which the battery pack is connected to the mobile terminal. In this way, information relating to the battery pack which has been connected the longest time ago can be erased or overwritten to enable new information relating to a newly connected battery pack can be stored in the memory means.
In addition, correction values and/or the timezone of the accurate time information can be advantageously stored for each battery pack in said memory means of the mobile terminal.